This invention relates to a rotational frequency sensing device comprising a pulse generating wheel, combined with a radial shaft sealing ring, for a machine element that can rotate about an axis.
A rotational frequency sensing device of this kind is known from U.S. Pat. No. 3,500,091 (corresponding to German Patent 19 11 513), the disclosure of which is hereby incorporated herein by reference. In that patent, arranged between the sealing lip of the radial shaft sealing ring 64 and the machine element 12 (on which a wheel is mounted for relative rotation) is a cylindrical sleeve 28 that contains a receptacle for the sensor 44, the pulse generating wheel being fastened to the radial shaft sealing ring 64. This configuration is difficult to manufacture and is sensitive to external damage which may impair its function.